Imperator

"Imperator Augustus" and "Imperatrix" redirect here. For the first Roman emperor, see Augustus. For the racehorse, see Imperatrix (horse). For the monarchic title of a head of state, see Emperor. For other uses, see Imperator (disambiguation).

Marble statue of Augustus of Prima Porta, showing him in a pose of imperator (1st century AD)
Carving in Diana Veteranorum referring to Lucius Verus as Imperator
Golden dedication inscription at the Äusseres Burgtor of the Hofburg Palace in Vienna of "FRANCISCUS I. IMPERATOR AUSTRIAE MDCCCXXIV" (Francis I. Emperor of Austria 1824), who ruled as Francis II, last Holy Roman Emperor until 1806
Politics of ancient Rome
Periods
Constitution
Political institutions
Assemblies
Ordinary magistrates
Extraordinary magistrates
Public law
Senatus consultum ultimum
Titles and honours

The title of imperator (/ˌɪmpəˈrɑːtər/ im-pə-RAH-tər) originally meant the rough equivalent of commander under the Roman Republic. Later, it became a part of the titulature of the Roman Emperors as their praenomen. The Roman emperors generally based their authority on multiple titles and positions, rather than preferring any single title. Nevertheless, imperator was used relatively consistently as an element of a Roman ruler's title throughout the Principate and the later Roman Empire. It was abbreviated to "IMP" in inscriptions. The word derives from the stem of the verb imperare, meaning 'to order, to command'. The English word emperor derives from imperator via Old French: Empereür.